A quick no brainer guide in choosing nib sizes in an overly complicated fountain pen world:

If you write small, go with an EFFor the normal writer, F is the most popularIf you tend to lean on a bigger font, M will be perfectB is for statements!! Sign a check in B, write a header in B, do some coloring/shading in BStub nibs are italic in writing style (have a special card or invitation to write?)